The present invention relates to a heat storage means comprising an inner container with a storage core therein, an outer container surrounding the inner container with clearance and so as to form a preferably evacuated insulating space, two ducts running from the outside through the insulating space into the inner container, one of such ducts serving as a supply duct for a heat vehicle fluid and the other thereof serving as a return line for same, the duct sections passing through the insulating space having a straight section extending outwards through the outer container and an elbow opening into the inner container and adjoining the said section, the part, which is adjacent to the outer container, of the duct sections being made so deformable that both the length of the duct in the deformable part thereof and in the course thereof its longitudinal direction may be adjusted.
A heat storage means of this type is described in the German patent publication DE 3,725,165-A. In this known design a straight duct section extends from the outer container to the bend, which at its lower and its top ends has respective short, bellows-like sections.
This arrangement makes it possible to allow for inaccuracies in manufacture during fitting, it both being possible to change the length of the duct between the bend and the outer container and also, within certain limits, the longitudinal direction of the duct section located between the bellows-like sections. Furthermore, it is possible to allow for expansion due to thermal effects.
When there is little space available it is important to keep the dimensions of the heat storage means as small as possible. In the case of the design of the said German patent publication DE 3,725,165-A the gap between the outer container and inner container is comparatively large.
During assembly the inner container is introduced into the outer container and secured in its position. When this is done the inner container is so offset out of its final position intended in the outer container that the duct ends extending past the periphery of the inner container do not hinder the introduction of the inner container. As soon as these duct ends are aligned with the apertures, provided for them, in the outer container, the inner container is placed in its final position, the duct ends being pushed through the apertures in an outward direction. Then the inner container is secured in its position, following which the duct ends are connected in a sealing manner with the outer container.
It has turned out that the gap between the outer container and the inner container may be reduced down to a few millimeters, as for example down to 5 mm, without affecting the function of the insulating space. On the other hand for reasons of manufacturing technology, it is necessary to cause the return duct to extend further out of the outer container in order to produce a reliable sealing joint in a relatively simple manner.
The reduction in the space required made possible by reducing the gap for the heat storage means is restricted by the fact that then the inner container is not able to be shifted sufficiently out of its final position during assembly in order to be able to insert the ducts into the inner container.